In the field of construction machines such as hydraulic excavators, wheeled loaders, dump trucks and bulldozers, electronic control of the engine and electroactuation/hybridization of the vehicle body have been promoted to decrease loads on environment or to cope with escalating resource prices. As a result, the construction machines now include many sensors represented by pressure sensors attached to them to achieve complicated controls.
The construction machines include dedicated controllers (control devices) for their respective functions such as controlling engines and hydraulic actuators, managing the operation states of the vehicle bodies and so on. Some of the controllers have a failure determination function to determine whether a predetermined control or controls are performed regularly or whether any abnormality of the sensor or sensors such as disconnection (breakage of wire) occurs.
Controllers having a failure determination function record the determined failures that are classified in the form of error codes depending on the content of the failure determined by this function. The controller itself, which stores the results of failure determination, is configured to periodically transmit information such as the error code or time of occurrence of failure to an information center via a wireless communication terminal. According to an established system, a service person of the manufacturer of the construction machine analyses the cause of failure of the vehicle body based on the various pieces of information collected at the information center. If the service person judges that some urgent repair is necessary, he holds in reserve necessary machinery and materials and goes off to the site to be able to quickly cope with the failure.
The content of the error codes collected at the information center in this manner does not always correspond to actual situation of the vehicle body. For instance, if the service person temporarily dismounts a part such as a sensor during maintenance work such as replacement of a part of the vehicle body and a failure diagnosis is performed in this state, the controller makes a decision that the sensor is disconnected and transmits an error code.
The service person who performs the work knows that this error code is a meaningless, false error code that is generated at the time of replacing the parts. However, other service persons cannot determine whether the error code concerned is true or false, so that they cannot properly cope with it. In addition, it is possible that this false error code will continue to be managed as a failure history and thus time may be consumed for the analysis of this meaningless false error code.
To solve such a problem, a controller is conventionally proposed as described in, for instance, PTL 1 below. This controller is configured such that when a service person connects a failure diagnosis device, which is able to collect abnormality information data, to the vehicle body at a service factory where maintenance work is often performed, the controller does not output to the outside any abnormality information detected. PTL 2 discloses a method of transmitting to the administrator only those error codes that satisfy a unified standard for error codes.